9. Pneumonia

Question 1

What is pneumonia?

Answer 1

1. At the basic level, it is something infecting and growing in the lungs.
2. It is an old disease but still a big problem.
3. Community-based pneumonia is often quite treatable.
4. around 450 million cases per year.
5. Major cause of death in all age groups.
6. Increasing AMR in some pneumonia causing pathogens but not all.
7. Problems with immunosuppressed and elderly patients as well as co-morbidities.

Question 2

How is pneumonia defined and diagnosed?

Answer 2

1. Presence of respiratory system like a cough and at least one other symptom like chest pain.
2. At least 1 systemic symptom like fever.
3. No other explanation for symptoms.
4. X-ray is needed for true diagnosis. Bacterial growth, mucus and inflammation create a cloudiness in the lungs.
5. Community diagnosis is hard due to access to outpatient X-rays and taking too long.

Question 3

How does pneumonia cause fever?

Answer 3

1. Usually due to high levels of inflammation, especially in gram-negative infections.
2. It can lead to capillary breakdown and blood leaking into the lungs.
3. The bacteria can then also get into the blood.
4. This is now a systemic infection and fever is a systemic symptom.

Question 4

What does hard diagnosis of community pneumonia lead to?

Answer 4

1. Treatment is based on symptoms without a true diagnosis.
2. This leads to excessive and preventative use of antimicrobials.
3. This can contribute to AMR.

Question 5

What are the 2 ways to classify pneumonia?

Answer 5

1. By place of acquisition.
2. By pathogen.

Question 6

What is the classification of pneumonia by place of acquisition?

Answer 6

1. Community acquired pneumonia. (CAP) This is often seasonal and associated with viral infections.
2. Hospital-acquired pneumonia. (HAP) Symptoms need to start during an >2 days hospital admission.
3. Ventilator-acquired pneumonia. (VAP) Associated with plastic tubes and the intubation process itself introduces bacteria to the lungs.

Question 7

What is the classification of pneumonia by pathogen?

Answer 7

1. Different places of acquisition are associated with different pathogens and therefore different antibiotic susceptibility.
2. Diagnostics to identify the pathogen that causes pneumonia is hard due to the large amounts of commensal bacteria in the throat and mouth.
3. Treatment is often a stab in the dark

Question 8

What is Health-care associated pneumonia (HCAP)?

Answer 8

1. Pneumonia with a direct association with healthcare.
2. But symptoms and treatment occur in the community.
3. Big worry in hospitals

Question 9

How are the different pneumonias defined?

Answer 9

CAP: symptoms develop in the community and within 48 hours of hospital admission.
HAP: Symptoms develop more then 48 hours after hospital admission.
VAP: Development of HAP associated with endotracheal tube insertion.

Question 10

How is HCAP defined?

Answer 10

1. Symptoms appear within 90 days of a >2 day hospital admission.
2. Usually resident of the nursing home or care facility.
3. attendance of a hospital clinic
4. Recent IV antibiotics, chemo or wound care.
5. Normally associated with picking up a colonising bacteria that later causes an infection
6. HCAP is more likely to occur if you have had antibiotics as it reduces competition from commensals.

Question 11

What is the epidemiology of CAP?

Answer 11

1. Incidence of CAP in adults annually is 5-10/1000 population.
2. High hospitalisation rate and produces a large burden on the NHS.
3. 1%-10% of hospitalised patients require ITU care but mortality is low.
4. Lung function can reduce very quickly, and low oxygen levels need supplementation and IV antibiotics.
5. It can deteriorate and kill quickly.
6. High cost of treatment

Question 12

What are the risk factors for CAP?

Answer 12

1. Age
2. Age is also associated with co-morbidities like heart disease, COPD and immune function.
3. Seasonal due to association with viral infection and bacterial colonisation.
4. Social factors like overcrowding and poverty and the ethnic groups that are more likely to live in these conditions.

Question 13

What are the most common causative pathogens for CAP?

Answer 13

1. S. pneumoniae
2. H. influnzae
3. However often we don’t know the cause

Question 14

How does COPD affect CAP?

Answer 14

1. It is very common
2. The trachea and bronchi are narrowed due to inflammation.
3. Often caused by smoking and industrial pollutants.
4. often caused H. Influenzae

Question 15

How does diabetes affect CAP?

Answer 15

1. Bacteraemia pneumococcal infections.
2. More likely to enter the blood due to the high levels of sugar in the blood
3. They are more likely to have burst capillaries.

Question 16

How does aspiration affect CAP?

Answer 16

1. Increases mucus in the lungs
2. Reduces the ability to cough and clear the pathogen

Question 17

How does alcoholism affect CAP?

Answer 17

1. Aspiration of bacteria in mucus
2. Aspiration of gut bacteria in vomit.

Question 18

Pneumonia-causing pathogens: S.pneumoniae

Answer 18

1. Most common due to good at evading the immune system due to polysaccharide capsule. Good at getting in the blood.
2. Gram positive coccus in chains or pairs.
3. Produces toxins like pneumolysin that cause lung damage.
4. Cause a large host inflammatory response.
5. Predisposing factors include: immune deficiencies, steroids, malnutrition, age, and smoking.
6. Colonises the nasopharynx in ~10% of adults.
7. Prevention includes vaccination against commonly circulating polysaccharide capsule.
8. Some immune deficient patients take antibiotic prophylaxis

Question 19

Resistance in S. pneumoniae

Answer 19

1. Increasing but not a big problem
2. This is due to not being good at picking up resistance.
3. S. pneuoniae doesn’t do horizontal gene transfer so relies of low frequency target site mutation

Question 20

Pneumonia-causing pathogens: H. influenzae

Answer 20

1. Gram negative cocco-bacillus.
2. Colonises nasopharynx of 75% of healthy humans.
3. Not as big problem due to successful vaccination.
4. Although it is gram-negative, it behaves like a gram-positive respiratory pathogen. It can produce ß-lactamses

Question 21

Pneumonia-causing pathogens: S. aureus

Answer 21

Rare but severe

Question 22

Pneumonia-causing pathogens: Enterobacterales

Answer 22

1. eg Klebsiella pneumoniae
2. More common in the elderly
3. More serious as it can cause haemorrhagic pneumonia

Question 23

What is atypical pneumonia?

Answer 23

1. Pneumonia-like syndromes that don’t respond to penicillin and where no causative organism can be found.
2. Due to various organisms like legionella
3. Common features include: resistant to ß-lactams, produce a more diffuse x-ray image, usually difficult to culture

Question 24

What is M. pneumoniae?

Answer 24

1. Common in children and young adults.
2. Lack a rigid cell wall but have a tri-laminar membrane.
3. Comes in waves around every 3-4 years.
4. Droplet transmission
5. 2-3 week incubation period
6. Usually a mild disease
7. Difficult to culture to difficult to treat.

Question 25

What is legionnaire's disease?

Answer 25

1. Mostly caused by L. pneumophilia 2. Small gram-negative coccobacilli 3. Discovered in 1976 after an outbreak in a hotel 4. It naturally lives in stagnant water like cold water storage tanks or AC units. 5. Infections is caused by inhalation of aerosols. 6. Not a lots of person to person transmission everyone just breathe it in from the same source.

Question 26

Why is microbiological diagnosis of pneumonia hard?

Answer 26

1. Hard to collect a sample 2. lots of organisms in the sample

Question 27

What are the advantages of accurate microbiological diagnosis of pneumonia?

Answer 27

1. Enables use of more narrow-spectrum antibiotics, which reduces overall use and potential side effects. 2. Decreases the development of resistance 3. Can allow pathogen identification

Question 28

How are blood cultures used for pneumonia diagnosis?

Answer 28

1. This is the best way to diagnose the causative agent. 2. It is sensitive but only work if the bacteria gets in to the blood. 3. Need to be cautious of antibiotics already in the blood.

Question 29

How are urine cultures used for pneumonia diagnosis?

Answer 29

Looking for surface structure of bacteria that are broken down and excreted.

Question 30

What is the epidemiology of HAP and VAP?

Answer 30

1. The most common HAI contributing to death. 2. affects about 1% of patients 3. VAP has a 25-50% mortality rate and increasing levels of MDR. 4. VAP usually effects ITU patients who are very sick anyway 5. Prevention is the key in these infections.

Question 31

What is the most common HAI?

Answer 31

UTIs

Question 32

What is the HAP pathogenesis?

Answer 32

1. Mostly gram-negative, so from the person's own flora 2. Also, from the environment or from healthcare workers hands. 3. All about breathing in things from the environment like from sinks or vases. 4. Risk factors include: sedation, intubation, vomiting, impaired swallowing and long hospital stay.

Question 33

How does sedation increase the risk of HAP?

Answer 33

It affects coughing and swallowing, which increases the chance of aspirating the bacteria.

Question 34

How does intubation increase the risk of HAP?

Answer 34

The point of intubation can cause bacteria from the gut to be vomited up

Question 35

What usually causes early HAP?

Answer 35

Community organism

Question 36

What usually causes late HAP?

Answer 36

Antibiotic-resistant hospital opportunistic pathogens

Question 37

Pathogens causing HAP: Pseudomonas aeruginosa

Answer 37

1. Gram negative aerobic bacillus 2. Widespread in the environment, especially hospitals. 3. colonises humans and is an opportunistic pathogen. 4. High levels of antibiotic resistance 5. Very adaptable 6. Highly virulent like exotoxins and endotoxins, porins and pili

Question 38

What is serratia?

Answer 38

1. A rare infection 2. Very common in the lungs 3. It is like a cross between an enterobacterales and pseudomonas. 4. It is a gut bacteria that acts like an environmental bacteria. 5. Rare as a bloodstream infection but can easily be breathed in

Question 39

Can MRSA cause pneumonia?

Answer 39

1. yes and it is highly resistant 2. Often comes from the healthcare workers 3. People going in for planned admissions are often screened for MRSA

Question 40

Why is VAP common?

Answer 40

1. Ventilation bypasses the natural mechanisms of immunity that remove bacteria from the lungs. 2. It allows direct access to the lungs from the outside. 3. A ventilator can also actively pump bacteria into the lungs

Question 41

How does endotracheal tube placement increase the risk of VAP?

Answer 41

1. Local damage can be caused during the insertion. This increases colonisation and decreases clearance. 2. Inhalation of aerosols. 3. Biofilms can form inside the tube and outside the tube at the point it contacts the trachea. 4. When the tube are flushed or the biofilm gets big enough they burst and go straight into the lungs

Question 42

What antibiotic use can increase the risk of VAP?

Answer 42

1. Broad-spectrum treatment like meropenem. 2. This kills the commensals which reduces competition 3. It also selects for resistant variants. 4. This causes the pathogen to take over.

Question 43

Where can the causative bacteria for VAP come from?

Answer 43

1. Other areas on the patient's body 2. From the flora

Question 44

What can happen to some treatable pneumonias?

Answer 44

They can mutate or acquire resistance very quickly

Question 45

What are risk factors for VAP?

Answer 45

1. Prolonged ITU stay 2. Sternal fracture 3. Previous broad spectrum antibiotic use 4. colonisation by resistant organisms 5. Sedation 6. Age

Question 46

What are some infection control measures to prevent pneumonia transmission in hospitals?

Answer 46

1. Screening swabs 2. Side rooms on ITU and wards 3. Barrier nurse 4. PPE 5. Hand washing 6. Screening other patients 7. Cleaning of equipment 8. Dedicate nurse

Question 47

What are some prevention measures specifically for VAP?

Answer 47

1. Disinfection of equipment 2. No routine changing of ventilator equipment 3. Sterile insertion and suctioning 4. Nurse head up to prevent secretions pooling 5. Sedation vacations 6. Extubate as soon as clinically safe 7. Selective decontamination.

Question 48

What is selective decontamination and why it is controversial?

Answer 48

1. It is giving patients a cocktail of antibiotics when the enter ITU to decolonised the entire flora from the person. 2. This is done to minimise the bacteria in the person and therefore the ITU. 3. Done in the Nederlands which is usually really tight on antibiotic use. 4. Controversial as it is seen as excessive and unnecessary use of antibiotics and doesn’t always benefit the patient. 5. The argument is it saves future use of antibiotics and prevents pneumonia in very sick people.